1. Field of the Invention
The present invention relates to an injection device, and more particularly for a needle protecting module of an injection device and an injection device with a needle protecting module for facilitating a safe injection practice.
2. Description of Related Art
With reference to FIGS. 18 and 19, a conventional syringe 1 has a tube body 10, a pushing stick module 11, a needle base 12, a needle body 13, an isolating tube 14, an inner tube 15, an outer tube 16, an elastic unit 17, a mounting tube 18, and a stopping unit 19. The pushing stick module 11 is slidably and airtightly mounted in the tube body 10. The needle base 12 is mounted around the front end of the tube body 10. The needle body 13 is connected with the needle base 12 parallel with the axis X of the tube body 10. The isolating tube 14 is connected with the needle base 12 and surrounds the needle body 13. The inner tube 15 is connected with the needle base 12 and surrounds the isolating tube 14. The outer tube 16 is connected with the needle base 12 and surrounds the isolating tube 14. The elastic unit 17 is inserted between the isolating tube 14 and the inner tube 15. The mounting tube 18 is inserted between the isolating tube 14 and the inner tube 15.
A first stopping surface 181 of the mounting tube 18 faces a tapered section 151 of the inner tube 15. A second stopping surface 182 of the mounting tube 18 faces a flange 161 of the outer tube 16. An abutting surface 191 of the stopping unit 19 selectively abuts the first stopping surface 181. A recessed portion 194 is formed between two inclined surfaces 192 and 193 and selectively abuts the tapered section 151.
Before injection, the elastic unit 17 abuts the mounting tube 18, such that the second stopping surface 182 abuts the flange 161, and the tapered section 151 abuts and is engaged with the recessed portion 194. Therefore, the stopping unit 19 is fixed in position. Also, the abutting surface 191 abuts the first stopping surface 181, such that the mounting tube 18 is also fixed in position.
During injection, the mounting tube 18 is pressed against the skin of the patient to push the stopping unit 19. The inclined surface 193 pushes the tapered section 151 to expand the inner diameter of the tapered section 151, such that the first stopping surface 181 can be inserted into the tapered section 151. Therefore, the mounting tube 18 can be inserted into the inner tube 15 during the injection process.
After injection, the elastic unit 17 pushes the mounting tube 18 to move away from the needle base 12. The first stopping surface 181 and the second stopping surface 182 are restricted by the tapered section 151 and the flange 161 respectively, such that the mounting tube 18 cannot move since the mounting tube 18 is left without the guiding of the stopping unit 19. Therefore, the mounting tube 18 can shelter the needle body 13 to isolate the needle body 13 away from the patient and the user.
However, the space between the isolating tube 14 and the inner tube 15 has to be large enough for accommodating the stopping unit 19 mounted between the isolating tube 14 and the inner tube 15, and the space also has to be reserved for elastic radial deformation of the inner tube 15 at the tapered section 151.
On the other hand, if the radial deformation is excessive, the mounting tube 18 cannot move smoothly. If the radial deformation is insufficient, the mounting tube 18 cannot be stopped effectively, such that the needle body 13 may be exposed outside. Therefore, the drawbacks of the conventional syringe 1 have to be resolved indeed.